Repeat the theory:
1. Self-induction is ____________________________________________________________
____________________________________________________________________________________________________________________________________________________________________________.
2. Inductance - ______________________________________________________________________________
__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
[L] = ______.
3. Self-induction emf : ______________, Where L- ______________________________, -_______________________Δ I - _______________________________.
4.Lenz's rule: ______________________________________________________________________________
5.Lenz's rule: ______________________________________________________________________________
_______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________.
6. The induced current arising in a closed circuit has a direction in which the own magnetic flux created by it through the area limited by the circuit tends to __________________ the change in the external magnetic flux that caused this current.
7. Magnetic flux passing through the solenoid Ф=________________.
8. Induction current is _______________________________________________________________________
_________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________.
9.Energy magnetic field W m =______________
10. Volumetric magnetic field energy density ω=__________________________.
Solve problems:
1. What is the inductance of the circuit if, at a current strength of 5A, a magnetic flux of 0.5 mWb appears in it?
Given: SI: Solution:
2. When the current in the coil decreases uniformly over 0.1 s from 10 A to zero, a self-inductive emf of 60 V arises in it. Determine the inductance of the coil.
Given: Solution:
3. Using a rheostat, the current in the coil is uniformly increased at a speed of 2 A/s. Coil inductance 200 mH. What is the self-induced emf in the coil?
Given: SI: Solution:
4. In a coil with an inductance of 0.6 H, the current is 20 A. What is the energy of the coil's magnetic field? How will the field energy change if the current strength is halved?
Given: Solution:
Answer: the magnetic field energy _____________ __________ times when the current is halved.
5. What should be the current strength in the winding of a choke with an inductance of 0.5 H in order for the field energy to be equal to 1 J?
Given: Solution:
6. What is the energy of the magnetic field of the solenoid, in which a magnetic flux of 0.3 Wb appears at a current strength of 1A?
Given: Solution:
check yourself:
1. What magnetic flux occurs in a circuit with an inductance of 0.2 mH at a current of 10 A?
Given: SI: Solution:
2. Find the inductance of the conductor in which a uniform change in current strength by 2A for 0.25 s excites a self-inductive emf of 20 mV.
Given: SI: Solution:
3. Find the energy of the magnetic field of the solenoid, in which a magnetic flux of 0.5 Wb appears at a current strength of 10A.
Given: Solution:
4. Coil inductance 0.1 mH. At what current strength will the magnetic field energy be equal to 0.2 mJ?
Given: SI: Solution:
Date “___” _________20____
Task 35
Independent work on this topic
"A magnetic field. Electromagnetic induction"
OPTION 1
1. A magnetic field is created
1) electric charges 2) magnetic charges
3) moving electric charges 4) any body
2. Magnetic induction lines around a current-carrying conductor are correctly shown in the case.
1) A 2) B 3) C 4) D
3. A straight conductor with current / is located between the poles of the magnet (the conductor is located perpendicular to the plane of the sheet, the current flows to the reader). The Ampere force acting on a conductor is directed
1) right → 2) left ← 3) up 4) down ↓
4. Flight trajectory of an electron flying into a uniform magnetic field at an angle of 60°
5. Which of the following processes is explained by the phenomenon electromagnetic induction?
1) interaction of conductors with current.
2) deflection of the magnetic needle when passing through the wire electric current.
3) 
the occurrence of an electric current in a closed coil when the current strength in the coil located next to it increases.
4) the occurrence of a force acting on a straight conductor carrying current.
6. A light wire ring suspended by a thread. When a magnet is pushed into the ring with the north pole, it will be:
1) repelled by a magnet 2) attracted to a magnet 3) stationary 4) first repelled, then attracted
7. 
The figure shows a graph of the current in the inductor versus time. The self-induction EMF module adopts highest value in the interim
1) from 0 s to 1 s 2) from 1 s to 5 s 3) from 5 s to 6 s 4) from 6 s to 8 s
8. Match technical devices from the left column of the table with physical phenomena, used in them, in the right column.
Phenomena Devices
A. electric motor 1) the effect of a magnetic field on permanent magnet
B. compass 2) the effect of a magnetic field on a moving electric charge
B. Galvanometer 3) the effect of a magnetic field on a current-carrying conductor
G. MHD - generator PART C
Solve the problem.
11. A conductor 1 m long slides along horizontal rails located in a vertical magnetic field with an induction of 0.01 T at a constant speed of 10 m/s. The ends of the rails are connected to a resistor with a resistance of 2 ohms. Find the amount of heat released in the resistor in 4 s. Neglect the resistance of the rails and conductor.
Given: SI: Solution
Rating _____ teacher signature ________________/L.S. Tishkina/
OPTION 2
PART A Choose one correct answer
1. A moving electric charge creates
1) only electric field 2) only magnetic field
3) both electric and magnetic fields 4) only gravitational field
2. The figure shows a cylindrical conductor through which electric current flows. The direction of the current is indicated by the arrow. What is the direction of the magnetic induction vector at point C?
1) in the drawing plane up
2) in the drawing plane down
3) from us perpendicular to the drawing plane
4) to us perpendicular to the drawing plane
3. A current-carrying conductor introduced into a magnetic field is acted upon by a force directed
“Rate of a chemical reaction” - Factors affecting the rate of a reaction. Mechanochemical sound activation. An example of writing a kinetic equation for a simple reaction. Speed of heterogeneous reactions. Chemical kinetics. Heterogeneous catalysis. Homogeneous catalysis. Pre-exponent and exponent. Graphic definition of n. The pre-exponential factor (A) gives some characteristic of the total number of collisions.
“Cosmic velocity” - The movement of a body in a gravitational field. Hyperbola. East. The trajectory of bodies moving at low speed. First escape velocity. Image of a man and a woman. Launched in 1977. Yu.A. Gagarin. Circle. In 1989, the Voyager spacecraft went beyond solar system. Trajectories of bodies.
“Reaction rate” - The area of contact of the reacting substances. Determine the type of responsive systems. Catalysts and catalysis. Effect of concentration of reactants (for homogeneous systems) 3rd row. Homogeneous systems: Gas + gas Liquid + liquid. 2. Write down the kinetic equation for the reaction: 2H2 + O2 = 2H2O. Factors affecting speed.
“Sound propagation speed” - What is a pure tone? This is why thunder lags so much after a flash of lightning. Spread speed sound waves V different environments not the same. What determines the timbre of a sound? Sound travels faster in liquids. Sound travels slowest in gases. IN solids- even faster.
“Measuring the speed of light” - The satellite was 22 minutes late to emerge from the shadows, compared to the rocket. Ole Christensen Römer September 25, 1644 – September 19, 1710. C=214300 km/s. Armand Hypollite Louis Fizeau September 23, 1819 – September 18, 1896. Then he reached the mirror, passed between the teeth and fell into the eye of the observer. The wheel rotated slowly and the light was visible.
“Lesson Speed time distance” - Speed = Distance: time. A man was walking into the city and on the way he caught up with three of his acquaintances. Warm up. The passenger train traveled 75 km in the first hour, 60 km in the second hour and 75 km in the third hour. A freight train traveled 120 km in 3 hours, covering the same distance every hour. Movement tasks. However, the return flight takes 80 minutes.
Self-induced emf With any change in the current in the coil (or in general in the conductor), a self-inductive emf is induced in it.
The greater the rate of change of current, the greater the self-induction emf.
Any decrease in electric current is accompanied by the appearance of e. d.s. self-induction, which, according to Lenz's rule, tends to maintain a decreasing current. As a result, the voltages on the inductors can increase significantly when the current circuit is broken. Sometimes these voltages are so high that the windings can burn out; to protect the windings, so-called discharge resistors are included in parallel with them.
Proportionality factorLis called inductance.Inductance is measured in Henry. An inductance of one henry is possessed by a circuit in which, when the current changes uniformly at a rate of one ampere per second, e.g. d.s., equal to one volt.
The inductance of a coil is a quantity that characterizes the property of a coil to induce a self-inductive emf.
The inductance of a given coil is a constant value, independent of both the strength of the current passing through it and the rate of its change.
We should not forget that if the current in the coil does not change, then no self-induction emf occurs. The phenomenon of self-induction is especially pronounced in a circuit containing a coil with an iron core, since iron significantly increases the magnetic flux of the coil, and therefore the magnitude of the self-induction emf when it changes.In practice, sometimes a coil (or winding) that does not have inductance is needed. In this case, the wire is wound onto a reel, having previously folded it in half. This winding method is called bifilar.
EMF mutual induction
To cause an induced emf in one coil by changing the current in another, it is not at all necessary to insert one of them inside the other, but you can place them side by side
And in this case, when the current in one coil changes, the resulting alternating magnetic flux will penetrate (cross) the turns of the other coil and cause an EMF in it.
Mutual induction makes it possible to connect various electrical circuits with each other through a magnetic field. Such a connection is usually called inductive coupling.
The magnitude of the mutual induction emf depends primarily on the speed at which the current in the first coil changes. The faster the current changes in it, the greater the mutual induction emf is created.
In addition, the magnitude of the mutual inductance emf depends on the inductance of both coils and their relative position, as well as on the magnetic permeability environment.In order to be able to distinguish between different pairs of coils according to their ability to mutually induce an emf, the concept of mutual inductance or mutual induction coefficient was introduced.
Mutual inductance is designated by the letter M. Its unit of measurement, like inductance, is henry.
Henry is the mutual inductance of two coils such that a change in current in one coil by 1 ampere per second causes an emf of mutual inductance equal to 1 volt in the other coil.
The magnitude of the EMF of mutual induction is affected by the magnetic permeability of the environment. The greater the magnetic permeability of the medium through which the alternating magnetic flux connecting the coils is closed, the stronger the inductive coupling of the coils and the greater the value of the mutual induction emf.
The operation of such an important electrical device as a transformer is based on the phenomenon of mutual induction.